"The president said that he didn't want to give tax breaks to the rich," Schumer said. "Then he should, this afternoon, denounce repeal of the estate tax, which goes exclusively to the rich when you repeal it."

Schumer went on to say that it was an "unpleasant surprise" for the Republicans to "slash" the top tax rate from 39.6 to 35 percent.

"The high-end one percent; they are doing great. God bless them. We're glad they are doing great. They don't need a tax break; middle-class people do," Schumer said.

"Look at what this plan does," Schumer added. "It gives huge tax cuts to the wealthiest and the biggest corporations, and socks it to the middle-class. Eliminating state and local deductibility is a blow to the wallet of millions of middle-class tax payers across the country."

The "Big Six," which includes the top House and Senate leaders, the chairmen of the two chambers' tax-writing committees, Treasury Secretary Steven Mnuchin and National Economic Council Director Gary Cohn, unveiled their plan on Wednesday to rewrite the tax code after months of negotiations. They are hopeful to have the bill on Trump's desk by the end of the year, according to Politico. As exemplified by Schumer, some aspects of the proposed plan in particular are expected to face scrutiny, Politico noted.

Though many supply-side Republicans are skeptical of the child tax credit, the Big Six is calling for a major expansion of the popular break, while offering no details on how it might be increased. They’re also proposing a new $500 credit for non-child dependents like seniors.

They want to repeal the estate tax along with the alternative minimum tax, which was originally meant to ensure that the wealthy don't avoid taxes altogether.

GOP lawmakers argue their aim is to simplify the current tax code, which many Americans complain is overly complicated and burdensome.

"We are committed to making sure the tax code is at least as progressive as the exiting tax code, that it does not shift the tax burden from high-income to low- and middle-income taxpayers," a senior administration official told reporters.

Their plan would make a number of other changes to the individual side of the code, including collapsing the number of tax brackets to three from seven, with the top rate set at 35 percent but leaving open the possibility that it could be set higher for some. They would nearly double the standard deduction to $24,000 for couples while getting rid of the personal exemption.